Plants convert the sun's energy into carbohydrates via photosynthesis.
        
             
        
        
        
A The continents were once joined together 
Explanation:
All the continents were once together making a huge one called Pangea. 
 
        
                    
             
        
        
        
Answer: Racial classification 
Explanation: Racial classification can be defined as the way humans are classified based on their physical and social traits which they have such as how they look, their skin color, hair texture, the native languages they speak. 
Scientists used racial classification to learn how unique and different humans are. 
 
        
             
        
        
        
When a single copy of a disease allele doesn't result in a disease but instead is good for the person or organism that carries it, we say that allele has a heterozygote advantage. In other words this occurs when heterozyhotes have increased fitness over both homozygotes.  A good example is sickcle cell trait, which protects against malaria in heterozygotes, but causes a deadly disease in homozygotes.